Time Travel

It might not appear to be a very big deal, but understanding time is not as simple as it may seem. The concept of time, as per the genius scientist Albert Einstein, is relative. Well, now what does being relative mean? It means that time passes at different rates for people who are moving relative to one another, although the effect is substantial only when the speed is close to that of light. Even this explanation does not clearly state what relativity means. Let us look at it from a different angle, which is more relatable. Imagine sitting in a boring lecture for 5 minutes. Even this amount of time seems like an era. Now imagine talking to a beautiful girl sitting next to you on a flight for an hour. Time really seems to fly here, doesn’t it? Well, that is the concept of relativity.

It is this feature of time that makes one wonder about the possibility of time travel. A classic example of this relative passage of time is the twin paradox. This states that when one travels in a spacecraft at an appreciable fraction of light speed for a few years and returns back to earth only to find one younger than expected, i.e., many more years may have passed on the earth than for the astronaut on the spacecraft. However, time and space are often seen as integrated and inseparable entities. One may imagine space-time being distributed over a 2D surface. As per the theory of relativity, the plane is flexible and it is this attribute that hints at the possibility of time travel.

Time travel is nothing but the hypothetical concept where a person or an entity can travel from one end of time (or space) to the other through a tunnel. Imagine a sheet of paper as the space-time plane. Let one end be the mouth at which the entity is supposed to enter and the other the destination. Now as per the concept of time travel, it is the travel through the tunnel. One might as well say that this is probably the same as travelling the entire distance. But the space-time plane is flexible and hence we can fold it over itself so that the gap between the two checkpoints is reduced, thereby enabling the entity to reach a significantly farther point in space and/or time instantly. So, it may simply be understood as a tunnel that significantly reduces the distance between two distant points in the universe through which one may travel well below the speed of light but yet be able to reach the destination. It should be noted that the maximum speed limit for any entity is considered as the speed of light. And this tunnel is basically known as a wormhole.

That being said, one might wonder- is time travel possible? I say, why not? There are several theories suggesting possible ways in which one can travel through time. Here are some that I found really interesting:

1.       Speed:

The easiest way to time travel is speed. As mentioned earlier, the twin paradox was actually an experiment in which twin atomic clocks were used. One was flown on a jet and the other was kept on the earth. It was found that the one on the jet moved slower than the one on earth. So, at velocities close to that of light, this may actually have a significant effect, thereby making travel to future possible. The fastest speed achieved on earth is that of a proton in the Large Hadron Collider, where it travels at 99.9999991% of light speed. Using special theory of relativity, it appears that one second for the proton is roughly 11 months for us…!

2.       Gravity:

Time travels slower for your feet than head. Sounds ridiculous, right? But it isn’t. This one is also backed by experimental results. To travel to the far future, all we need is a region of strong gravity, possibly a black hole. But it indeed is a risky business, slip beyond the boundary and you may never return. Scary….!

3.       Wormholes:

The gates, or tunnels, which keep popping up every now and then at a quantum scale, serve as a bridge between two very distant points in the universe. However, the energy required to amplify that to human scale is humongous and practically impossible (for now). The incompatibility between general relativity and quantum mechanics poses a huge challenge. But I am sure in the near future we might just be able to bridge them. Fingers crossed.

Apart from these there are many other theories enumerating various ways of travelling through time. It is a dimension we haven’t been able to comprehend yet. Although travelling to the future may be the easiest time travel, it also provides us the opportunity to travel to the past too. This is explained by the classic grandfather paradox, which basically explains preventing one’s birth by killing their grandparents. If one travels back in time and kills their grandparents before the conception of their parents, then one prevents one’s own birth, and hence the subsequent events like the time machine is never even invented and one is erased out of existence. Way too paradoxical, isn’t it? However, several scientists like the late famous professor Stephen Hawking argued that travelling to the past may not be possible.

Despite its complexity and integrated existence with space, there are significant efforts being put forth by scientists in understanding the mechanics. I am certainly hopeful to see a time machine being built in my lifetime. Aren’t you?

Written by

Divyajyoti Biswal